307-OR: Impaired Differentiation of Trpv1-Positive Adipose Progenitors Activates Compensatory Thermogenic Mechanisms

Brown and beige thermogenic adipocytes are specialized in energy consumption and linked to metabolic health. Canonically, thermogenic adipocytes are thought to be derived from mesenchymal PdgfRα+ adipocyte progenitor cells (APC) . We recently identified a novel population of cold-recruited APCs from the vascular smooth muscle lineage marked by the expression of the ion channel Trpv1 in mouse adipose tissue. To determine the function of the Trpv1+ APC-derived adipocytes, we impaired their adipogenic capacity by deletion of Pparγ in Trpv1-expressing cells in mice (Trpv1-Cre::Pparγ-flox) . Inhibition of de novo adipogenesis from Trpv1+ APCs resulted in modest changes in brown adipose tissue, but it caused a marked reduction in the expression of cold-induced browning genes, including UCP1, in white adipose tissue (WAT) , indicating impaired beige adipogenesis. Interestingly, Trpv1-Cre::Pparγ-flox mice did not show altered weight gain, glucose tolerance, or insulin sensitivity on either regular chow or high-fat diets. This discrepancy led us to search for potential compensatory mechanisms. We observed increased PdgfRα expression in WAT of Trpv1-Cre::Pparγ-flox animals, suggesting that impaired adipogenic capacity of the Trpv1+ APCs may trigger recruitment of the PdgfRα+ APCs. Additionally, while UCP1 expression was noticeably reduced in the beige adipocytes within WAT, the expression of transcripts involved in the UCP1-independent thermogenic pathways, including Ckmt1, Gatm, and Slc6a8, key components of the creatine futile cycle, was increased in the WAT of the Trpv1-Cre::Pparγ-flox mice upon cold exposure. Together, these data highlight a potential distinction between the thermogenic pathways mediated by adipocytes derived from the Trpv1+ versus those derived from the PdgfRα+ APCs. This functional difference of thermogenic adipocytes could be critical in designing strategies to target these cells as a therapeutic approach for metabolic diseases.